Process gas delivery for semiconductor process chambers

ABSTRACT

Methods for gas delivery to a process chamber are provided herein. In some embodiments, a method may include flowing a process gas through one or more gas conduits, each gas conduit having an inlet and an outlet for facilitating the flow of gas through the gas conduits and into a gas inlet funnel having a second volume, wherein each gas conduit has a first volume less than the second volume, and wherein each gas conduit has a cross-section that increases from a first cross-section proximate the inlet to a second cross-section proximate the outlet but excluding any intersection points between the gas inlet funnel and the gas conduit, and wherein the second cross-section is non-circular; and delivering the process gas to the substrate via the gas inlet funnel.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 12/197,029, filed Aug. 22, 2008, which is herein incorporatedby reference.

FIELD

Embodiments of the present invention generally relate to semiconductorprocessing equipment, and more specifically to methods for introducing aprocess gas into a semiconductor process chamber.

BACKGROUND

In some semiconductor process chambers, multiple process gases can bedelivered to the process chamber through a common gas inlet, forexample, a gas injection funnel disposed in the ceiling of a processchamber. Such semiconductor process chambers may include those used forchemical vapor deposition (CVD) or atomic layer deposition (ALD) whereinthe process gases may be utilized to at least partially deposit a layeron a substrate.

The volume of a common gas inlet can be substantially greater than thevolume of a gas conduit which supplies a process gas to the inlet.Consequently, the process gas rapidly expands when entering the inlet.The rapid expansion of the process gas can result in cooling of theprocess gas—an effect known as Joule-Thompson Cooling. Process gaseshaving low vapor pressures, for example hafnium tetrachloride (HfCl₄),will condense upon cooling, thus forming particles that may contaminatethe inlet or result in concentration variation in the process gas.

Further, tangential alignment of a gas conduit relative to a centralaxis of the common gas inlet can result in a circulating gas vortex inthe gas inlet and over the substrate. The vortex can cause the processgas, for example, comprising a carrier gas and a reactant vapor, tobecome separated resulting in concentration variations in the processgas.

Accordingly, there is a need in the art for a gas delivery assembly thatprevents rapid cooling and vortex formation.

SUMMARY

Methods and apparatus for a gas delivery assembly are provided herein.In some embodiments, the gas delivery assembly includes a gas inletfunnel having a first volume and one or more gas conduits; each gasconduit having an inlet and an outlet for facilitating the flow of a gastherethrough and into the first volume, wherein each gas conduit has asecond volume less than the first volume, and wherein each gas conduithas a cross-section that increases from a first cross-section proximatethe inlet to a second cross-section proximate the outlet, wherein thesecond cross-section is non-circular.

In some embodiments, an apparatus for processing a substrate includes aprocess chamber having an inner volume and a gas delivery assemblycoupled to the process chamber for introducing a process gas into theinner volume. The gas delivery assembly may be the same as discussedabove.

In some embodiments, a method for processing a substrate includesflowing a process gas through one or more first volumes into a secondvolume, wherein each first volume has a cross-section that increasesfrom a first cross-section proximate to a second cross-section along alongitudinal axis in the direction of flow, wherein the secondcross-section is non-circular, and wherein the second volume is greaterthan each first volume; and delivering the process gas to the substratevia the second volume.

Methods for gas delivery to a process chamber are provided herein. Insome embodiments, a method may include flowing a process gas through oneor more gas conduits, each gas conduit having an inlet and an outlet forfacilitating the flow of gas through the gas conduits and into a gasinlet funnel having a second volume, wherein each gas conduit has afirst volume less than the second volume, and wherein each gas conduithas a cross-section that increases from a first cross-section proximatethe inlet to a second cross-section proximate the outlet but excludingany intersection points between the gas inlet funnel and the gasconduit, and wherein the second cross-section is non-circular; anddelivering the process gas to the substrate via the gas inlet funnel.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a schematic cross-sectional view of a process chamber inaccordance with some embodiments of the present invention.

FIGS. 2A-B are schematic side views of a gas delivery assembly and gasconduit in accordance with some embodiments of the present invention.

FIGS. 3A-B are schematic top views of a gas delivery assembly inaccordance with some embodiments of the present invention.

FIG. 4 is a method for processing a substrate in accordance with someembodiments of the present invention.

DETAILED DESCRIPTION

Methods and apparatus for a gas delivery assembly are provided herein.In some embodiments, the gas delivery assembly includes a gas inletfunnel having a first volume and one or more gas conduits; each gasconduit having an inlet and an outlet for facilitating the flow of a gastherethrough and into the first volume, wherein each gas conduit has asecond volume less than the first volume, and wherein each gas conduithas a cross-section that increases from a first cross-section proximatethe inlet to a second cross-section proximate the outlet, wherein thesecond cross-section is non-circular. The gas delivery assembly may becoupled to a process chamber for facilitating the introduction ofprocess gases thereto. Process gases may include, for example, a hafniumprecursor such as hafnium tetrachloride (HfCl₄) or other low vaporpressure reactant gases flowed in combination with a carrier gas thatmay benefit from a reduction in Joule-Thompson cooling and/or the gasseparation caused by vortex formation provided by embodiments of thepresent invention, and discussed below.

“Atomic Layer Deposition” (ALD) or “cyclical deposition” as used hereinrefers to the sequential introduction of two or more reactive compoundsto deposit a layer of material on a substrate surface. The two, three ormore reactive compounds may alternatively be introduced into a reactionzone of the processing chamber. Usually, each reactive compound isseparated by a time delay to allow each compound to adhere and/or reacton the substrate surface. In one aspect, a first precursor or compoundA, such as a hafnium precursor, is pulsed into the reaction zonefollowed by a first time delay. Next, a second precursor or compound B,such as an oxidizing gas, is pulsed into the reaction zone followed by asecond delay. The oxidizing gas may include several oxidizing agent,such as in-situ water and oxygen. During each time delay a purge gas,such as nitrogen, is introduced into the processing chamber to purge thereaction zone or otherwise remove any residual reactive compound orby-products from the reaction zone. Alternatively, the purge gas mayflow continuously throughout the deposition process so that only thepurge gas flows during the time delay between pulses of reactivecompounds. The reactive compounds are alternatively pulsed until adesired film or film thickness is formed on the substrate surface. Ineither scenario, the ALD process of pulsing compound “A”, purge gas,pulsing compound B or purge gas is a cycle. A cycle can start witheither compound A or compound B and continue the respective order of thecycle until achieving a film with the desired thickness.

FIG. 1 is a schematic cross-sectional view of a process chamber 100 inaccordance with some embodiments of the present invention. The processchamber 100 includes a gas delivery assembly 130 adapted for cyclicdeposition, such as atomic layer deposition (ALD) or rapid chemicalvapor deposition (rapid CVD). The terms ALD and rapid CVD as used hereinrefer to the sequential introduction of reactants to deposit a thinlayer over a substrate. The sequential introduction of reactants may berepeated to deposit a plurality of thin layers to form a conformal layerof a desired thickness.

The process chamber 100 comprises a chamber body 104 having sidewalls110 and a bottom 106. A slit valve 102 in the process chamber 100provides access for a robot (not shown) to deliver and retrieve asubstrate 112 within the process chamber 100. In some embodiments of thepresent invention, the substrate 112 can be a semiconductor wafer with adiameter of 200 mm or 300 mm or a glass substrate. The process chamber100 can include any suitable chamber configured for ALD or rapid CVDthat may benefit from the inventive apparatus and methods disclosedherein. Some exemplary process chambers are described in commonlyassigned United States Patent Application Publication No. 2005-0271813,filed on May 12, 2005, entitled “Apparatuses and Methods for AtomicLayer Deposition of Hafnium-Containing High-K Dielectric Materials,” andUnited States Patent Application Publication No. 2003-0079686, filed onDec. 21, 2001, entitled “Gas Delivery Apparatus and Method for AtomicLayer Deposition”, which are both incorporated herein in their entiretyby references. Two exemplary chambers suitable for performing at leastsome of the inventive techniques may include GEMINI ALD or CVD chambersavailable from Applied Materials, Inc.

A substrate support 108 supports the substrate 112 on a substratereceiving surface 191 in the process chamber 100. The substrate support(or pedestal) 108 is mounted to a lift motor 114 to raise and lower thesubstrate support 108 and the substrate 112 disposed thereon. A liftplate 116 connected to a lift motor 118 is mounted in the processchamber 100 and raises and lowers pins 120 movably disposed through thesubstrate support 108. The pins 120 raise and lower the substrate 112over the surface of the substrate support 108. In some embodiment of thepresent invention, the substrate support 108 may include a vacuum chuck,an electrostatic chuck, or a clamp ring for securing the substrate 112to the substrate support 108 during processing.

The substrate support 108 may be heated to increase the temperature ofthe substrate 112 disposed thereon. For example, the substrate support108 may be heated using an embedded heating element, such as a resistiveheater, or may be heated using radiant heat, such as heating lampsdisposed above the substrate support 108. A purge ring 122 may bedisposed on the substrate support 108 to define a purge channel 124which provides a purge gas to a peripheral portion of the substrate 112to prevent deposition thereon.

The gas delivery assembly 130 is disposed at an upper portion of thechamber body 104 to provide a gas, such as a process gas and/or a purgegas, to the process chamber 100. For example, and in some embodiments, aprocess gas may include a hafnium precursor or other suitable reactantgases having a low vapor pressure, and a carrier gas. A vacuum system178 is in communication with a pumping channel 179 to evacuate anydesired gases from the process chamber 100 and to help in maintaining adesired pressure or a desired pressure range inside a pumping zone 166of the process chamber 100.

The gas delivery assembly 130 may further comprise a chamber lid 132.The chamber lid 132 can include a gas inlet funnel 134 extending from acentral portion of the chamber lid 132 and a bottom surface 160extending from the gas inlet funnel 134 to a peripheral portion of thechamber lid 132. The bottom surface 160 is sized and shaped tosubstantially cover the substrate 112 disposed on the substrate support108. The chamber lid 132 may have a choke 162 at a peripheral portion ofthe chamber lid 132 adjacent the periphery of the substrate 112. The capportion 172 includes a portion of the gas inlet funnel 134 and the gasinlets 136A, 136B, 136C, 136D. The gas inlet funnel 134 has the gasinlets 136A, 136B, 136C, 136D to provide gas flows from two similarvalves 142A, 142B, 142C, 142D. The gas flows from the valves 142A, 142B,142C, 142D may be provided together and/or separately.

Embodiments of the gas inlet assembly that may facilitate reducedJoule-Thompson Cooling and gas separation caused by vortex formation arediscussed below with respect to FIGS. 2A-B and 3A-B. Generally, suchembodiments relate to the cross-sectional shape of one or more gasconduits 150 and their orientation with respect to the gas inlet funnel134

FIGS. 2A-B depict a three dimensional view of a portion of the gasdelivery assembly 130 including the gas inlet funnel 134 and one or moregas conduits 150 in accordance with some embodiments of the presentinvention. Referring to FIG. 1, the gas conduits 150A, 150B, 150C, and150D are disposed between the gas inlets 136A, 136B, 136C, 136D and thevalves 142A, 142B, 142C, 142D

The gas inlet funnel 134 depicted in FIG. 2A may be generallycylindrical in shape and having a first volume and a central axisdisposed therethrough. In some embodiments, such as depicted in FIG. 1,the gas inlet funnel 134 can have a cross-section expanding along atleast a portion of the central axis and in the direction of gas flow.The gas inlet funnel 134 may comprise one or more tapered inner surfaces(not shown), such as a tapered straight surface, a concave surface, aconvex surface, or combinations thereof or may comprise sections of oneor more tapered inner surfaces (i.e., a portion tapered and a portionnon-tapered).

The gas conduits 150A, 150B, 150C, and 150D are coupled to the gas inletfunnel 134 at the gas inlets 136A, 136B, 136C, and 136D, respectively.Each gas conduit as illustrated in FIG. 2B has an inlet 151 and anoutlet 152 for facilitating the flow of a process gas therethrough alonga longitudinal axis and into the first volume define by the gas inletfunnel 134 via each gas inlet 136. Each gas conduit 150 defines a secondvolume that is less than the first volume of the gas inlet funnel 134.The difference between the first and second volumes may be such that, inthe absence of the present invention, a process gas flowing from thesecond volume of a gas conduit 150 into the first volume of the gasinlet funnel may experience a Joule-Thompson Cooling effect which canresult in the formation of fine particles from the process gas andconcentration variations in the process gas delivered to the substrate.

To reduce Joule-Thompson Cooling, each gas conduit 150 may be shaped forhaving a cross-section that increases from a first cross-sectionproximate the inlet 151 to a non-circular, second cross-sectionproximate the outlet 152. The increasing cross-section along thedirection of gas flow between the inlet 151 and the outlet 152 expandsthe volume gradually in the gas conduit, thereby maintaining chemicalequilibrium in, for example, a low vapor pressure reactant gas. Thus,the gradual expansion of the cross-section of each gas conduit 150 canreduce a rapid temperature drop in the reactant gas. In someembodiments, and by way of non-limiting example, the first cross-sectionproximate the inlet 151 can be circular. However, any suitable shape forthe first cross-section can be selected.

The second cross-section proximate the outlet 152 of each gas inlet 150may be non-circular. As depicted in FIG. 2B, the second cross-sectionmay be generally rectangular; however, other suitable shapes may becontemplated. In some embodiments, the ratio of the area of the firstcross-section to the area of the second cross-section is about 3:1 orgreater. Those skilled in the art may utilize other ratios such as tomanage the temperature drop in the process gas caused by Joule-ThompsonCooling along an expanding cross-section of each gas conduit between theinlet 151 and the outlet 152.

In some embodiments, a non-circular shape is chosen for the secondcross-section such that the shape maximized the surface area of gasconduit contacted by a process gas flowing therethrough. Suchnon-circular shapes which maximize surface area can be chosen, forexample, and in some embodiments, where external heaters are coupled tothe outer surface of each gas conduit. The external heaters may provideheat as a further means of reducing the Joule-Thompson Cooling caused byan expanding cross-section of each gas conduit between the inlet 151 andthe outlet 152. The maximized surface area of the second-cross sectioncontacting the heater can facilitate maximum heat transfer alongsecond-cross section.

Returning to FIG. 2A, and in some embodiments, each gas conduit 150 hasa longitudinal axis 152 that intersects the central axis 154 of the gasinlet funnel 134. Such an orientation may provide laminar flow of theprocess gas in the gas inlet funnel 134, thus reducing vortex formation.Further, laminar flow in the gas inlet funnel 134 may improve purging ofthe inner surface of the gas inlet funnel 134 and other surfaces of thechamber lid 132.

Further, and by way of non-limiting example, each gas conduit 150 mayhave a longitudinal axis that is perpendicular to the central axis ofthe gas inlet funnel 134, such as depicted in FIG. 2A for gas conduits150A, 150B, 150C, and 150D. However, one or more gas conduits 150 may beangled with respect to the central axis of the gas inlet funnel 134 asnecessary.

In some embodiments, at least two gas conduits may have longitudinalaxes 152 that are diametrically opposed. For example, and depicted inFIG. 2A, gas conduits 150A, 150B and gas conduits 150C, 150D havelongitudinal axes 152 diametrically opposed. The diametrically opposedlongitudinal axes intersect the central axis of the gas inlet funnel 134as illustrated in top view in FIG. 3A.

Other configurations of the gas conduits 150 are possible. In someembodiments, and depicted in top view in FIG. 3B, at least two gasconduits, such as gas conduits 150A, 150B, may have perpendicularlongitudinal axes 156, 158 intersecting the central axis 154 of the gasinlet funnel 134. Those skilled in the art may utilize one or moreorientations of the gas conduits, 150A, 150B, 150C, 150D along the gasinlet funnel 134 as discussed above.

Returning to FIG. 1, and in some embodiments, the valves 142A, 142B,142C, and 142D are coupled to separate reactant gas sources but arepreferably coupled to the same purge gas source. For example, the valve142A is coupled to a reactant gas source 138A and valve 142B is coupledto reactant gas source 138B, and both valves 142A, 142B are coupled tothe purge gas source 140. Each valve 142A, 142B, 142C, 142D includes adelivery line 143A, 143B, 143C, and 143D. The delivery line 143A, 143B,143C, 143D is in communication with the reactant gas source 138A, 138B,138C, 138D and is in communication with the gas inlet 136A, 136B, 136C,136D of the gas inlet funnel 134 through the gas conduits 150A, 150B,150C, 150D. In some embodiments, additional reactant gas sources,delivery lines, gas inlets and valves may be added to the gas deliveryassembly 130. The purge lines, such as 145A, 145B, 145C, and 145D, arein communication with the purge gas source 140, and the flows of thepurge lines, 145A, 145B, 145C, and 145D, are controlled by valves, 146A,146B, 146C, and 146D, respectively. The purge lines, 145A, 145B, 145C,and 145D, intersect the delivery line 143A, 143B, 143C, 143D at thevalves, 142A, 142B, 142C, and 142D. If a carrier gas is used to deliverreactant gases from the reactant gas source 138A, 138B, 138C, 138D, inone embodiment the same gas is used as a carrier gas and a purge gas(e.g., nitrogen used as a carrier gas and a purge gas). The valves,142A, 142B, 142C, and 142D, comprise diaphragms. In some embodiments,the diaphragms may be biased open or closed and may be actuated closedor open, respectively. The diaphragms may be pneumatically actuated ormay be electrically actuated. Examples of pneumatically actuated valvesinclude pneumatically actuated valves available from Swagelock of Solon,Ohio. Pneumatically actuated valves may provide pulses of gases in timeperiods as low as about 0.020 second. Electrically actuated valves mayprovide pulses of gases in time periods as low as about 0.005 second. Anelectrically actuated valve typically requires the use of a drivercoupled between the valve and the programmable logic controller, such as148A, 148B.

Each valve 142A, 142B, 142C, 142D may be adapted to provide a combinedgas flow and/or separate gas flows of the reactant gas 138A, 1388, 138C,138D and the purge gas 140. In reference to the valve 142A, one exampleof a combined gas flow of the reactant gas 138A and the purge gas 140provided by the valve 142A comprises a continuous flow of a purge gasfrom the purge gas source 140 through the purge line 145A and pulses ofa reactant gas from the reactant gas source 138A through the deliveryline 143A.

The delivery lines, 143A, 143B, 143C, and 143D of the valves, 142A,142B, 142C, and 142D, are coupled to the gas inlets, 136A, 136B, 136C,and 136D, through the gas conduits, 150A, 150B, 150C, and 150D. The gasconduits, 150A, 150B, 150C, and 150D, may be integrated or may beseparate from the valves, 142A, 142B, 142C, and 142D. In one embodiment,the valves 142A, 142B, 142C, 142D are coupled in close proximity to thegas inlet funnel 134 to reduce any unnecessary volume of the deliveryline 143A, 143B, 143C, 143D and the gas conduits 150A, 150B, 150C, 150Dbetween the valves 142A, 142B, 142C, 142D and the gas inlets 136A, 136B,136C, 136D.

The gas inlets 136A, 136B, 136C, 136D are located adjacent to the upperportion 137 of the gas inlet funnel 134. In other embodiments, one ormore gas inlets 136A, 136B, 136C, 136D may be located along the lengthof the gas inlet funnel 134 between the upper portion 137 and the lowerportion 135.

At least one portion of the bottom surface 160 of the chamber lid 132may be tapered from the gas inlet funnel 134 to a peripheral portion ofthe chamber lid 132 to help in providing an improved velocity profile ofa gas flow from the gas inlet funnel 134 across the surface of thesubstrate 112 (i.e., from the center of the substrate 112 to the edge ofthe substrate 112). In some embodiments, the bottom surface 160 maycomprise one or more tapered surfaces, such as a straight surface, aconcave surface, a convex surface, or combinations thereof. In someembodiments, the bottom surface 160 is tapered in the shape of a funnel.

A control unit 180, such as a programmed personal computer, work stationcomputer, or the like, may be coupled to the process chamber 100 tocontrol processing conditions. For example, the control unit 180 may beconfigured to control flow of various process gases and purge gases fromthe gas sources 138A, 138B, 138C, 138D, 140 through the valves 142A,142B, 142C, 142D, 146A, 146B, 146C, 146D during different stages of asubstrate process sequence. Illustratively, the control unit 180comprises a Central Processing Unit (CPU) 182, support circuitry 184,and a memory 186 containing associated control software 183. The controlunit 180 may control each component of the process chamber 100 directly,as illustrated by the plurality of control lines 188 coupling thecontrol unit 180 to each chamber component. Alternatively, the controlunit 180 may be coupled to, and control, the individual control units(not shown) of each chamber system. For example, the control unit 180may be coupled to an individual control unit (not shown) of the gasdelivery assembly 130, where the individual control unit of the gasdelivery assembly 130 controls each component thereof, for example, gassources 138A-D.

FIG. 4 illustrates a method for processing the substrate 112 inaccordance with some embodiments of the present invention. Processingmay include, for example, depositing a hafnium oxide (HfO_(x)) film atopa substrate by an ALD process. The deposition process includes providinga hafnium precursor, generally in combination with a carrier gas such asnitrogen (N₂), that may either be subject to Joule-Thompson Cooling in arapidly expanding volume, or separation from the carrier gas as a resultof vortex formation when entering a gas inlet funnel. Thus, theembodiments of the gas conduits 150 and gas inlet funnel 134 describedabove may be advantageously utilized with the method 400 to prevent suchundesirable effects.

The method 400 is described with reference to the process chamber 100depicted in FIG. 1. At step 402, the substrate 112 is loaded into aprocess chamber 100.

At step 404, gases are flowed through one or more first volumes (i.e.,gas conduits 150) into a second volume (i.e., gas inlet funnel 134). Insome embodiments, a hafnium precursor is flowed through one gas conduit150 and an oxygen-containing precursor is flowed through another gasconduit 150. The hafnium precursor and oxygen-containing precursor maybe pulsed separately, or simultaneously in an ALD process to form ahafnium oxide film on the substrate 112.

The gas inlet funnel 134 and the gas conduits 150 may be arranged in anysuitable arrangement as discussed above. Minimally, and as discussedabove each gas conduit 150 has a longitudinal axis that intersects thecentral axis of gas inlet funnel 134. This orientation mayadvantageously prevent vortex formation as a gas flows out a gas conduit150 and into the gas inlet funnel 134. Further, and as discussed above,each gas conduit 150 minimally has a cross-section that increases alonga longitudinal axis from a first cross-section to a secondcross-section, wherein the second cross-section is non-circular. Thegeometry of the gas conduits may advantageous reduce Joule-ThompsonCooling and provide more surface area for heat transfer as discussedabove.

In some embodiments, the temperature drops along the gas conduits 150A,150B, 150C, and 150D as gases (e.g., hafnium precursor and carrier gas)flow through each gas conduit. The temperature drops only slightly fromabout 190 to about 183 degrees Celsius, in contrast to a largetemperature drop of about 200 degrees Celsius to 108 degrees Celsius ina conventional design. Conventional design may be, for example, a gasconduit having a rapidly expanding cross-section. Maintaining thetemperature of each gas conduit 150 above about 180 degrees Celsiushelps to keep the hafnium precursor in vapor form. In some embodiments,and as discussed above, heaters may be coupled to each gas conduit 150and utilized to further reduce the temperature drop of a process gasflowing through each gas conduit 150.

At step 406, the gases are delivered to the substrate 112 via the secondvolume (i.e., gas inlet funnel 134). In some embodiments, a hafniumprecursor is introduced to the process chamber 100 via the gas conduit150 and gas inlet funnel 134 at a rate from about 5 mg/m to about 200mg/m. The hafnium precursor is usually introduced with a carrier gas,such as nitrogen, with a total flow rate in the range from about 50 sccmto about 2,000 sccm. In conventional ALD processes, the hafniumprecursor is pulsed into the process chamber 100 at a duration fromabout 1 second to about 10 seconds, depending on the particular processand desired hafnium-containing compound. In advanced ALD processes, thehafnium precursor is pulsed into the process chamber 100 at a shorterduration from about 50 ms to about 3 seconds. In some embodiments, thehafnium precursor may be hafnium tetrachloride (HfCl₄). In someembodiments, the hafnium precursor may be tetrakis (diethylamine)hafnium ((Et₂N)₄Hf or TDEAH).

The oxygen-containing precursor is introduced to the process chamber 100at a rate in the range from about 10 sccm to about 1,000 sccm,preferably in the range from about 30 sccm to about 200 sccm. Forconventional ALD processes, the oxidizing gas is pulsed into the processchamber at a rate from about 0.1 second to about 10 seconds, dependingon the particular process and desired hafnium-containing compound. Inadvanced ALD processes, the oxidizing gas is pulsed into the processchamber at a shorter duration from about 50 ms to about 3 seconds.

The substrate 112 is then exposed to pulse of a hafnium precursor thatis introduced into the process chamber 100 for a time period in a rangefrom about 0.1 second to about 5 seconds. Next, a pulse of anoxygen-containing precursor is introduced into the processing chamber100. In some embodiments, the oxygen-containing precursor may includeseveral oxidizing agents, such as in-situ water and oxygen. Suitablecarrier gases or purge gases may include helium, argon, nitrogen,hydrogen, forming gas, oxygen and combinations thereof. A “pulse” asused herein is intended to refer to a quantity of a particular compoundthat is intermittently or non-continuously introduced into a reactionzone of the processing chamber 100.

After each deposition cycle, a hafnium-containing compound, such ashafnium oxide, having a particular thickness will be deposited on thesurface of the substrate 112. In some embodiments, each deposition cycleforms a layer with a thickness in the range from about 1-10 Angstroms.Depending on specific device requirements, subsequent deposition cyclesmay be needed to deposit hafnium-containing compound having a desiredthickness. As such, a deposition cycle can be repeated until the desiredthickness for the hafnium-containing compound is achieved. Thereafter,the process is stopped, when the desired thickness is achieved.

Hafnium oxide deposited by an ALD process has the empirical chemicalformula HfO_(x). The hafnium oxide has the molecular chemical formulaHfO₂, but by varying process conditions (e.g., timing, temperature,precursors), hafnium oxide may not be fully oxidized, such asHfO_(1.8+). Preferably, hafnium oxide is deposited by the processesherein with the molecular chemical formula of about HfO₂ or less.

In some embodiments, the cyclical deposition process or ALD process ofFIG. 1 occurs at a pressure in the range from about 1 Torr to about 100Torr, preferably in the range from about 1 Torr to about 20 Torr, forexample from about 1 Torr to about 10 Torr. In some embodiments, thetemperature of the substrate 112 is usually in the range from about 70degrees Celsius to about 1,000 degrees Celsius, preferably from about100 degrees Celsius to about 650 degrees Celsius, more preferably fromabout 250 degrees Celsius to about 500 degrees Celsius.

The hafnium precursor is generally dispensed to the process chamber 100by introducing carrier gas into a bubbler containing the hafniumprecursor. Suitable bubblers, such as PROE-VAP™, are available fromAdvanced Technology Materials, Inc., locate in Danbury, Conn. Thetemperature of the bubbler is maintained at a temperature depending onthe hafnium precursor within, such as from about 100 degrees Celsius toabout 300 degrees Celsius. For example, the bubbler may contain HfCl₄ ata temperature from about 150 degrees Celsius to about 200 degreesCelsius.

In some embodiments, the oxidizing gas is produced from a water vaporgenerating (WVG) system that is in fluid communication to the processchamber 100 by a line. The WVG system generates ultra-high purity watervapor by means of a catalytic reaction of O₂ and H₂. The WVG system hasa catalyst-lined reactor or a catalyst cartridge in which water vapor isgenerated by means of a chemical reaction, unlike pyrogenic generatorsthat produce water vapor as a result of ignition. Regulating the flow ofH₂ and O₂ allows the concentration to be precisely controlled at anypoint from 1% to 100% concentrations. The water vapor may contain water,H₂, O₂ and combinations thereof. Suitable WVG systems are commerciallyavailable, such as the WVG by Fujikin of America, Inc., located in SantaClara, Calif. and the CSGS (Catalyst Steam Generator System) by UltraClean Technology, located in Menlo Park, Calif.

The pulses of a purge gas, preferably argon or nitrogen, are introducedat a rate between about 1 slm to about 20 slm, preferably at a ratebetween about 2 slm to about 6 slm. Each processing cycle lasts fromabout 0.01 seconds to about 20 seconds. For example, in someembodiments, the processing cycle is about 10 seconds, while in someother embodiment, the processing cycle is about 2 seconds. Longerprocessing steps lasting about 10 seconds deposit excellenthafnium-containing films, but the throughput is reduced. The specificpressures and times are obtained through experimentation.

Many precursors are within the scope of the invention. One importantprecursor characteristic is to have a favorable vapor pressure.Precursors at ambient temperature and pressure may be gas, liquid orsolid. However, within the ALD chamber, volatilized precursors areutilized. Organometallic compounds or complexes include any chemicalcontaining a metal and at least one organic group, such as amides,alkyls, alkoxyls, alkylamidos and anilides. Precursors may compriseorganometallic, inorganic and halide compounds.

An exemplary ALD process is a hafnium oxide film grown by sequentiallypulsing a hafnium precursor with in-situ steam formed from a watergenerator. A substrate surface is exposed to a pretreatment to formhydroxyl groups. The hafnium precursor, HfCl₄, is maintained in aprecursor bubbler at a temperature from about 150-200 degrees Celsius.Carrier gas, such as nitrogen, is directed into the bubbler with a flowrate of about 400 sccm. The hafnium precursor saturates the carrier gasand is pulsed into the chamber for 3 seconds. A purge gas of nitrogen ispulsed into the chamber 100 for 3 seconds to remove any unbound hafniumprecursor. Hydrogen gas and oxygen gas with the flow rate of 120 sccmand 60 sccm respectively, are supplied to a water vapor generator (WVG)system. The in-situ steam exits from the WVG with approximately 60 sccmof water vapor. The in-situ steam is pulsed into the chamber for 1.7seconds. The purge gas of nitrogen is pulsed into the chamber 100 for 4seconds to remove any unbound or non-reacted reagents, such asbyproducts, hafnium precursor, oxygen and/or water or any by-productssuch as HCl. The temperature of the substrate 112 is maintained at atemperature between about 400-600 degrees Celsius. Illustratively, eachALD cycle may form about 0.8 Angstroms of a hafnium oxide film.

Although the embodiments of the invention are described to deposithafnium-containing compounds, a variety of metal oxides and/or metalsilicates may be formed outside of the hafnium-containing compounds byalternately pulsing metal precursors with oxidizing gas derived from aWVG system, such as a fluid of water vapor and O₂. The ALD processesdisclosed above may be altered by substituting the hafnium and/orsilicon precursors with other metal precursors to form materials, suchas hafnium aluminates, titanium silicates, zirconium oxides, zirconiumsilicates, zirconium aluminates, tantalum oxides, tantalum silicates,titanium oxides, titanium silicates, silicon oxides, aluminum oxides,aluminum silicates, lanthanum oxides, lanthanum silicates, lanthanumaluminates, nitrides thereof, and combinations thereof.

Methods and apparatus for a gas delivery assembly are provided herein.The gas delivery assembly may advantageously provide reducedJoule-Thompson Cooling through gas conduits having an expandingnon-circular cross-section, and optionally coupled to external heaters.The orientation of the gas conduits such that the longitudinal axis ofeach conduit intersects the central axis of the gas inlet funnel mayadvantageously reduce vortex formation in the gas inlet funnel.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

1. A method for processing a substrate, comprising: flowing a processgas through one or more gas conduits, each gas conduit having an inletand an outlet for facilitating the flow of gas through the gas conduitsand into a gas inlet funnel having a second volume, wherein each gasconduit has a first volume less than the second volume, and wherein eachgas conduit has a cross-section that increases from a firstcross-section proximate the inlet to a second cross-section proximatethe outlet but excluding any intersection points between the gas inletfunnel and the gas conduit, and wherein the second cross-section isnon-circular; and delivering the process gas to the substrate via thegas inlet funnel.
 2. The method of claim 1, wherein the longitudinalaxes of each gas conduit intersects with a central axis of the gas inletfunnel.
 3. The method of claim 2, wherein each gas conduit has alongitudinal axis that is perpendicular to the central axis of the gasinlet funnel.
 4. The method of claim 2, wherein each gas conduit has alongitudinal axis that is disposed at an angle to the central axis ofthe gas inlet funnel.
 5. The method of claim 2, further comprising:flowing the process gas from at least two gas conduits, wherein the atleast two gas conduits have diametrically opposing longitudinal axesthat are aligned with each other.
 6. The method of claim 2, furthercomprising: flowing the process gas from at least two gas conduits,wherein the at least two gas conduits have perpendicular longitudinalaxes.
 7. The method of claim 1, further comprising: heating the processgas flowing through each gas conduit.
 8. The method of claim 1, whereinthe gas inlet funnel has an increasing cross-section along at least aportion of the central axis and in the direction of gas flow.
 9. Themethod of claim 1, further comprising: providing at least one of hafniumtetrachloride (HfCl₄) or tetrakis diethylamine hafnium ((Et₂N)₄Hf) asthe process gas.
 10. The method of claim 1, wherein the process gascomprises a hafnium precursor and an oxygen-containing precursor, andwherein flowing the process gas further comprises: flowing the hafniumprecursor through a first gas conduit of the one or more gas conduits;and flowing the oxygen-containing precursor through a second gas conduitof the one or more gas conduits.
 11. The method of claim 10, furthercomprising alternately providing the hafnium precursor and theoxygen-containing precursor to form a hafnium oxide film on thesubstrate.
 12. The method of claim 1, wherein the ratio of thecross-sectional area at the outlet to the cross-sectional area at theinlet is about 3:1 or greater.
 13. The method of claim 1, wherein thefirst cross-section proximate the inlet is circular and the secondcross-section proximate the outlet is rectangular.
 14. A computerreadable medium having instructions stored thereon that, when executed,cause a substrate processing chamber to perform a method on a substrate,the method comprising: flowing a process gas through one or more gasconduits, each gas conduit having an inlet and an outlet forfacilitating the flow of gas through the gas conduits and into a gasinlet funnel having a second volume, wherein each gas conduit has afirst volume less than the second volume, and wherein each gas conduithas a cross-section that increases from a first cross-section proximatethe inlet to a second cross-section proximate the outlet but excludingany intersection points between the gas inlet funnel and the gasconduit, and wherein the second cross-section is non-circular; anddelivering the process gas to the substrate via the gas inlet funnel.15. The computer readable medium of claim 14, wherein the method furthercomprises: heating the process gas flowing through each gas conduit. 16.The computer readable medium of claim 14, wherein the method furthercomprises: providing at least one of hafnium tetrachloride (HfCl₄) ortetrakis diethylamine hafnium ((Et₂N)₄Hf) as the process gas.
 17. Thecomputer readable medium of claim 14, wherein the process gas comprisesa hafnium precursor and an oxygen-containing precursor, and whereinflowing the process gas further comprises: flowing the hafnium precursorthrough a first gas conduit of the one or more gas conduits; and flowingthe oxygen-containing precursor through a second gas conduit of the oneor more gas conduits.
 18. The computer readable medium of claim 17,further comprising alternately providing the hafnium precursor and theoxygen-containing precursor to form a hafnium oxide film on thesubstrate.